The present invention generally relates to mechanisms that act to support an item while at the same time allowing the item to move across a support surface. In particular, the present invention relates to using a retractable roller mechanism that provides a static support upon the support surface when the item, such as an article of furniture has a relatively high force towards the support surface causing the roller mechanism to retract, when the item has a relatively lower force towards the support surface the roller mechanism automatically separates the static support from the support surface thereby allowing a roller to freely move the item along the support surface.
There has long been a desire to move large, bulky, and unwieldy items easily across a support surface with a minimum of effort while at the same time having the item not be unstable along the support surface during the times when it is desired that the item not to be easily moved across the support surface. This desire to have a roller mechanism or castor mechanism have two position states, being a first or operative state where the roller serves to allow the item to be easily moved along the support surface and a second or inoperative state wherein the roller becomes inoperative not allowing the item to be easily moved along the support surface, is well recognized in the prior art.
Previous approaches to this problem have often resulted in complex caster mechanisms that required the item to be lifted in order to actuate the caster into the previously mentioned first operating state from the second operating state or vice versa. The problem with this approach was that it required the item to be lifted, which is unsatisfactory because the desire to avoid lifting the item is the reason for providing roller mechanisms in the first place. Even if a particular item is not all that heavy, the size and bulk of the item usually makes it difficult for an individual to simultaneously lift the item and operate the roller mechanism to change the operating state, in addition most items have multiple roller mechanisms which require a single individual to lift the item multiple times at different locations. The aforementioned complex caster mechanisms have sometimes included jacks, in which the item can be raised and lowered to effectuate the roller mechanism changing its operating state, however, these mechanisms were still difficult to use for two reasons. First, if the item was located in a confined area or space, the jack mechanism was difficult to access, and secondly, the location of the jack, typically being on the bottom of the item could be difficult for an individual to be able to reach to the jack mechanism while simultaneously attempting to lift the item. Other approaches to this problem have included using a spherical roller mechanism that fits inside a mating socket, wherein the socket is retractable into a separate housing to provide both static support on the support surface when the spherical roller and socket assembly are retracted into the housing and when the spherical roller and socket assembly are extended from the housing allowing the item to be moved along the support surface. The problem with the spherical roller is that it operated at a close clearance with the socket assembly and was prone to ingesting foreign material into this close clearance, such as carpet fibers, when the spherical roller was moving across the support surface which caused a high degree of a frictional resistance to the spherical roller rotating. This resistance to rotation by the spherical roller made it difficult to move the item along the support surface. Another problem with the spherical roller was that it had a small contact area with the support surface which increased the unit loading that the spherical roller placed upon the support surface from the weight of the item, this in turn increased the likelihood of damage to the support surface from the spherical roller.
There remains a need for a retractable roller mechanism that supports an item while providing the two desired position states of being operative to allow the item to move along a support surface and being inoperative to statically support the item upon the support surface, without the need for an individual to lift the item or operate the mechanism while at the same time being adaptable to a varying support surface types, minimizing damage to the support surface, and being a simple to construct.
It is an object of the present invention to provide an improved retractable roller mechanism that can be operated conveniently by the normal forces that are applied to the item on which the roller mechanism is mounted, without the requirement of an individual having to access the roller mechanism itself.
It is a further object of the present invention to provide a retractable roller mechanism wherein the roller is automatically retracted into and and in an inoperative state by a exerting a force that is greater than the normal weight of the item from the item to the support surface, allowing the item to assume a static or stationary position for the period of time in which the force is continuously applied.
Still another object of the present invention is to provide a retractable roller mechanism wherein the roller is automatically placed into an operative state, and permitting free movement of the item along the support surface when the force from the item to the support surface is equal to the normal weight of the item.
Yet another object of the present invention is to provide a retractable roller mechanism of simple non castor construction that allows only bi-directional movement of the item while the roller mechanism is in the operative state.
It is another object of the presence invention to provide a retractable roller mechanism that while in an operative state has a roller that is adaptable to varying support surface types.
It is yet another object of the present invention to provide a retractable roller mechanism that while in an operative state or in inoperative state will result in none or minimal damage to the support surface.
It is further yet another object of the present invention to provide a retractable roller mechanism that is constructed of a minimum number of parts for ease of manufacture and lower unit costs.
The present invention is an improved retractable roller mechanism that statically supports an item upon a support surface in an inoperative state and supports the item to roll along the support surface in an operative state. Broadly, the mechanism includes a housing with a symmetrical axis, a roller frame that is slidably engaged with the housing for reciprocative movement relative to the housing, a spring, and a roller. The frame has an inoperative position state wherein the frame is retracted such that the housing rests on an statically contacts the support surface while supporting the item, the frame also has an operative position state provided by the spring bias wherein the frame is extended from the inoperative position state. The roller is rotatably mounted in the frame and is disposed to roll along the support surface when the frame is in the operative position state such that the housing is not in contact with support surface allowing the item to roll along the support surface. The retractable roller mechanism in the operative state allows only bi-directional movement along the support surface, the frame and roller are not castered with the roller having a rotational axis that is perpendicular to and intersects the housing axis.
These and other objects of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of the preferred embodiment of the present invention when taken together with the accompanying drawings, in which: